For we are the circumcision, who worship by the Spirit of God and glory in Christ Jesus and put no confidence in the flesh.
Praise God for His Holy Spirit, for it is by the Spirit of God that our worship has been redirected from earthly things to a Holy God! It is by the Spirit of God that our own spirit can rejoice in the Lord. It's by the Spirit that the knowledge of who God is is made known to me, and my eyes are opened and my heart abounds in the glorious worship of his renown that is all around. By the Spirit of God I taste and see that the Lord is good (Ps34:8)!. By the Spirit of God, mere songs become offerings of praise, and our minuscule voices become a sweet sweet sound to the ears of our God. By the Spirit of God our bodies have been transformed into a Holy place of worship:
Do you not know that you are God's temple and that God's Spirit dwells in you? If anyone destroys God's temple, God will destroy him. For God's temple is holy, and you are that temple.~1 Cor.3:16-17
The Spirit of God has become the enabler to sinful mankind! The Holy Spirit has enabled us to fulfill that which we were created for...communion with God centered on His glory! The Holy Spirit opens our eyes to all that the Father is worth...thus enabling us to be the worshipers God created and is now seeking(Jn.4:23-24).
So all of that probably doesn't even dent all that the holy Spirit does in our lives concerning our worship, but it is certainly enough to see how foolish it would be to put our confidence in anything other than the Spirit of God!
Paul had a strong case for why he could be confident in His flesh. He did a lot of the right things, learned the right stuff, but apart from Christ, Paul knew firsthand that there was nothing! So it can't be about us! It can't be about what we know, how good of a singer we are, or how eloquent of a Bible teacher we are, etc...Where we begin to find confidence in our flesh, we begin to see our worship misdirected; Directed away from our Holy triune God, from whom only true worship flows, and onto our own efforts, attempts, and insufficiencies.
The beauty of true worship is that I don't have what it takes, but through the divine working of the trinity, the Holy Spirit initiates, stirs up, and takes our worship to our High Priest Jesus who can offer it wholly and acceptable to our God! That is worth my confidence. Jeremiah 9:23 says,
"Let not the wise man boast in his wisdom, let not the mighty man boast in his might, let not the rich man boast in his riches, but let him who boasts boast in this, that he understands and knows me, that I am the LORD who practices steadfast love, justice, and righteousness in the earth. For in these things I delight, declares the LORD."
We can find plenty of earthly things to boast In or put our confidence in, but they will always disappoint. Our God will not disappoint, and He has given us His very Spirit to move us into a right heart of worship to our Righteous God. If you will boast, let us boast in the Lord together!